Comparison of radiocesium concentration changes in leguminous and non-leguminous herbaceous plants observed after the Fukushima Daiichi Nuclear Power Plant accident

Transfer of radiocesium from soil to crops is an important pathway for human intake. In the period from one to two years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, food monitoring results showed that radiocesium concentrations in soybean (a legume) were higher than those in other annual agricultural crops; in these crops, root uptake is the major pathway of radiocesium from soil to plant. However, it was not clear whether or not leguminous and non-leguminous herbaceous plants have different Cs uptake abilities from the same soil because crop sample collection fields were different. In this study, therefore, we compared the concentrations of Cs-137 in seven herbaceous plant species including two leguminous plants (Trifolium pratense L and Vicia sativa L) collected in 2012-2016 from the same sampling field in Chiba, Japan that had been affected by the FDNPP accident fallout. Among these species, Petasites japonicus (Siebold & Zucc.) Maxim. showed the highest Cs-137 concentration in 2012-2016. The correlation factor between all concentration data for Cs-137 and those for K-40 in these seven plants was R = 0.54 (p < 0.001) by t-test, thus potassium uptake ability by species would affect radiocesium uptake; however, for each species, no correlation between Cs-137 and K-40 was found. Interestingly, K-40 concentrations in T. pratense, V. sativa and Poaceae family plants did not differ significantly, but Cs-137 data in the Poaceae family plants were significantly lower than those in T. pratense (p < 0.001) and V. sativa (p = 0.017). The results indicated that leguminous species would have higher Cs-137 uptake ability than Poaceae family plants. (C) 2017 Elsevier Ltd. All rights reserved.